Epitaxial radiation heated reactor

ABSTRACT

Apparatus and process for vapor depositing epitaxial films on substrates. A gaseous reactant is introduced into a reaction chamber formed from a material, such as quartz, which is transparent and non-obstructive to radiant heat energy transmitted at a predetermined short wave length. A graphite susceptor, which is opaque to and absorbs the radiant heat energy, is positioned within the reaction chamber and supports the substrates to be coated. The susceptor is heated while the walls of the reaction chamber remain cool to preclude deposition of epitaxial film on the walls. To insure uniform heating of the susceptor, the same may be moved relative to the radiant heat source which, in the preferred embodiment, comprises a bank of tungsten filament quartz-iodine high intensity lamps which transmit radiant heat energy against the susceptor as a non-focused generally uniform energy field.

This application is a continuation of application Ser. No. 475,051,filed May 31, 1974, now abandoned, which in turn is a continuation ofapplication Ser. No. 195,504 filed Nov. 3, 1971, now abandoned, which inturn is a division of application Ser. No. 866,473, filed Oct. 15, 1969,now U.S. Pat. No. 3,623,712, issued Nov. 30, 1971.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of vapor deposition of films onsubstrates. More particularly, the field of this invention involves thevapor deposition of epitaxial films, for example silicon dioxide andlike films, on exposed surfaces of articles, such as silicon wafersubstrates commonly used in the electronics industry. Gaseous chemicalreactants are brought into contact with a heated substrate within areaction chamber the walls of which are transparent to radiant heatenergy transmitted at a predetermined short wave length. A susceptor,which absorbs energy at the wavelength chosen, supports the substrate tobe coated and heats the same as a result of its absorption of the heatenergy transmitted into the reaction chamber from the radiant heatsource employed.

2. Description of the Prior Art

While substrates, such as silicon wafers, have been coated heretoforewith epitaxial films, such as silicon dioxide or like films, so far asis known, the specific and improved vapor deposition procedure andapparatus disclosed herein are novel. The apparatus and process of thisinvention are effective to produce uniform film coatings on substratesunder controlled conditions so that coated substrates of high qualityand excellent film thickness uniformity are producible within closelycontrolled limits.

In chemical deposition systems, it is highly desirable to carry out thedeposition reaction in a cold wall type reaction chamber. By maintainingthe reaction chamber walls in the unheated state, such walls receivelittle or no film deposition during substrate coating. Cold wall systemsare additionally desirable because they permit the deposition of highpurity films, such as silicon dioxide films. Impurities can be evolvedfrom or permeate through heated reaction chamber walls. Because suchimpurities would interfere with and adversely affect the purity of thesubstrate coating, cold wall reaction chambers are employed to precludesuch impurity evolution or permeation.

To avoid such problems, chemical deposition processes have beendeveloped heretofore which permit heating of a substrate positionedwithin a reaction chamber without simultaneously heating the reactionchamber walls. Heretofore, the most successful of such processesinvolved the use of radio frequency (RF) induction heating of aconducting susceptor positioned within the reaction chamber, the wallsof which were formed of non-conducting or insulating material. Forexample, RF heating of a graphite susceptor within a quartz reactionchamber for depositing epitaxial silicon films has been known generallyheretofore.

However, such an RF heating technique, while it generally produces thestated objective in a cold wall reaction chamber, has several inherentand important disadvantages which make the same undesirable under manycircumstances. For example, an expensive and bulky RF generator isrequired which is very space consuming and which must be located closeto the epitaxial reactor. Also, the high voltages required with the RFcoils produce substantial personnel hazards, and RF radiation from theRF coils can and frequently does interfere with adjacent electricalequipment. Furthermore, such an RF procedure requires the utilization ofan electrically conducting susceptor for supporting the substrates to beheated. Also, RF systems are considerably more expensive overall thanthe simplified radiation heated system disclosed herein which weredesigned to replace the RF systems utilized heretofore.

SUMMARY OF THE INVENTION

This invention relates generally to an improved procedure for coating asubstrate with an epitaxial film and to an improved apparatus foreffecting such procedure. More particularly, this invention relates to avapor deposition apparatus and process for depositing an oxide, nitride,metal or other similar films in epitaxial fashion on a substrate, suchas on a silicon wafer commonly employed in the electronics industry inthe manufacture of integrated circuits, transistors and the like. Stillmore particularly this invention relates to a cold wall epitaxialreactor and process for coating substrates without utilizing radiofrequency induction heating of the type heretofore employed in cold wallvapor deposition systems.

In the subject procedure, a reaction zone, defined by an enclosedreaction chamber the walls of which are formed from a predeterminedmaterial specially selected for use in the reaction, has one or moresubstrates to be epitaxially coated positioned therein. In the preferredembodiment, a susceptor is utilized to support the substrates in thereaction chamber. A gaseous chemical mixture, composed of one or moresuitable reactants, is introduced into the reaction chamber into contactwith the heated substrates. Such substrates are heated from a radiantnon-RF heat source without simultaneously heating the walls of thereaction chamber so that the substrates become coated with the epitaxialreactant material while the walls remain uncoated.

Disadvantages inherent with prior known RF induction heated systems areovercome with the more compact radiation heated system of this inventionwhich transmits heat as a generally uniform energy field from aradiation heat source positioned outside the reaction chamber. Thefrequencies of the radiated heat energy and of the material from whichthe reactor walls are formed selected so that the radiant heat energy istransmitted at a wave length which passes through the walls of thereaction chamber without being absorbed by the same so that the wallsremain cool and essentially unheated.

When the substrates to be coated are suitably heated by the energyabsorbed by the susceptor, a gaseous reactant mixture is introduced intothe reaction chamber into contact with the substrates to effectepitaxial coating thereof in known fashion. In that regard, any of thegaseous chemical reactants commonly used in epitaxial coating proceduresmay be employed with the present invention.

An improved heat source preferably employed with the present systemcomprises a high intensity, high temperature lamp which operates at afilament temperature in the range of 5000° to 6000° F., by way ofexample. The lamp actually chosen is selected from the type whichproduces radiant heat energy in the short wave length range, preferablyapproximately 1 micron or below. Radiant energy in such short wavelengths passes through materials found suitable for defining the wallsof the reaction chamber, of which quartz is preferred. Quartz wallspossess excellent radiant energy transmission characteristics at thewave length noted so that little or no radiation is absorbed by thewalls, thus retaining the advantages of cool wall reaction system notedpreviously.

From the foregoing it should be understood that objects of thisinvention include the provision of an improved cold wall process forepitaxially coating a substrate with a film of a predetermined type; theprovision of a gaseous deposition apparatus for vapor depositing anepitaxial film on a heated substrate; the provision of improvedapparatus and process for epitaxially coating substrates by employing aradiant energy heat source which transmits generally uniform non-focusedheat energy in short wave lengths through the walls of a reactionchamber which are transparent and nonobstructive to such energy at thewave length chosen; the provision of an improved apparatus and methodwhich utilizes an opaque susceptor for heating substrates supportedthereon within a reaction chamber, the walls of which are defined by amaterial which is transparent to radiant heat energy while the susceptoris opaque to and absorbs such heat energy so that heating of thissusceptor is effected; and the provision in a radiation heated reactorof a heat source defined by one or more high intensity lamps whichtransmit radiant energy at a shortwave length which readily passesthrough without heating a reactor chamber wall.

These and other objects of this invention will become apparent from astudy of the following description in which reference is directed to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view, largely schematic in nature,through one embodiment of the subject apparatus.

FIG. 2 is a vertical sectional view through the apparatus taken in theplane of line 2--2 of FIG. 1.

FIG. 3 is a vertical sectional view corresponding generally to FIG. 2showing a modified embodiment of the subject apparatus.

FIG. 4 is a vertical sectional view through another modified embodimentof the apparatus.

FIG. 5 is an isometric view of a portion of the apparatus of FIG. 4.

FIG. 6 is a vertical sectional view through a further modification ofthe apparatus.

FIG. 7 is a sectional view taken in the plane of line 7--7 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Several embodiments of apparatus designed to carry out the improvedepitaxial deposition procedure of this invention are disclosed herein.Each of such embodiments employs the same basic concepts characteristicof the improved features of this invention, namely the utilization of acold wall reaction chamber in which a substrate to be epitaxially coatedis positioned, preferably upon a susceptor which is opaque and absorbsradiant heat energy transmitted through the walls of the reactionchamber without absorption by such walls. The source for such radiantheat comprises a high intensity lamp, or bank of such lamps, whichproduces and transmits high temperature heat energy at a wave lengthwhich is not interferred with by the walls of the reaction chamber.

The chemical epitaxial deposition procedure within the reaction chamberis essentially the same as that employed heretofore with known coatingprocedures. Therefore, only brief reference herein is directed to theconcepts of epitaxial film growth which are well known and understood inthe chemical vapor deposition art. By way of introductory example,however, the apparatus and process of this invention are utilizable toproduce various epitaxial films on substrates, such as silicon wafers.The system of this invention employs chemical reaction and/or thermalpyrolysis to deposit a variety of films, such as silicon, siliconnitride, and silicon dioxide, as well as metal films such as molybdenum,titanium, zirconium and aluminum, in accordance with reactions such asthe following:

Silicon epitaxial growth by silane or silicon tetrachloride pyralysis attemperatures within the range of 900°-1200° C. occurs as follows;

    SiH.sub.4 .sup.Heat Si + 2H.sub.2

    siCl.sub.4 + 2H.sub.2 → Si + 4HCl

Silicon nitride deposition may be effected at temperatures in the rangeof 600° to 1100° C. in accordance with reaction such as the following;

    3SiH.sub.4 + 4NH.sub.3 → Si.sub.3 N.sub.4 + 12 H.sub.2

    3siCl.sub.4 + 4NH.sub.3 → Si.sub.3 N.sub.4 + 12 HCl

Deposition of silicon dioxide from silane or silicon tetrachloride maybe effected in accordance with the following reaction at temperatures of800° to 1100° C.;

    SiH.sub.4 + H.sub.2 + 2CO.sub.2 → SiO.sub.2 + 3H.sub.2 + 2CO

    siCl.sub.4 + 2H.sub.2 + 2CO.sub.2 → SiO.sub.2 + 4HCl + 2CO

at somewhat lower temperatures, silicon dioxide deposition from silaneoxidation in the range of 300° to 500° C. may be effected as follows;

    SiH.sub.4 + O.sub.2 → SiO.sub.2 + 2H.sub.2

also, metal deposition at temperatures in the range of 900° to 1200° C.can be produced in accordance with the following exemplary reaction:

    2MoCl.sub.5 + 5H.sub.2 → 2Mo + 10 HCl

Corresponding reactions for producting other exemplary metal andnon-metal films as noted above also can be employed in accordance withknown procedures. The above reactions are intended as examples ofprocedure for which a cold wall deposition system is highly effectiveand alternative uses of such a system by those skilled in the chemicaldeposition art will become apparent from the following detaileddescription.

Apparatus of the type described herein has been effectively used forproducing silicon nitride and silicon dioxide dielectric films with filmthickness uniformity of ± 5% from wafer to wafer within a run. Highlyeffective results can be insured because operating temperatures can beclosely controlled and uniformly held due to use of the novel heatsource employed herewith.

Referring first to the apparatus embodiment shown in FIGS. 1 and 2, itshould be understood that the reactor structure is shown in generallyschematic fashion and is intended to be enclosed within a surroundingenclosure (not shown) in and on which the necessary gaseous reactantflow controls, electrical power sources, and other attendant mechanismsare intended to be housed and mounted. For purposes of clarity ofillustration, only those portions of the reactor necessary toillustrates the inventive concepts disclosed herein have been shown inthe drawings. It will be understood that those portions of the reactorillustrated are intended to be supported within the aforementionedenclosure in any suitable fashion.

The radiation heated reactor of FIGS. 1 and 2, generally designated 1comprises an elongated housing generally designated 2 defined as bestseen in FIG. 2 by opposed sidewalls 3 and 4 and a removable top closure6, the latter being slidable along or otherwise separable from the uppermargin of the sidewalls 3 and 4 to permit access to the hollow interior7 of the housing. Opposite ends of the housing, designated 8 and 9, maybe closed off in any suitable fashion, such as by employing end walls orthe like so that the interior 7 of the housing is completely enclosed.However, access into the hollow interior through one end of the housingis necessary so that substrates to be coated can be loaded and unloadedtherefrom prior to and following deposition coating thereof. Suitableaccess doors (not shown) may be provided in the end wall 9 of thehousing and in the reaction chamber to be described so that such accessmay be had to the reaction chamber.

Preferably the inner surfaces 11 of each of the confining walls of thehousing and of the top closure thereof are formed of a highly polishedreflecting material, such as polished sheet aluminum. Such reflectingsurfaces are provided to permit maximum utilization of the heatgenerated by the heat source to be described.

Such heat source is designated 12 and extends laterally across thehousing as seen in FIG. 2 and is secured in position by fastening thesame to suitable portions of the housing sidewalls. The heat sourcecomprises at least one high intensity lamp capable of producing andtransmitting radiant heat energy at a short wave length, preferably onewhich is approximately 1 micron or less.

In the embodiment illustrated, the heat source comprises a bank of suchlamps, each designated 13, which are mounted in threaded sockets 14 in apair of side by side lamp mounting blocks 16. The electrical connectionsfor the lamps are not illustrated but such connections are conventional.The upper open end of each lamp socket 14 is formed as an enlargedsemispherical recess 17 which is highly polished to serve as areflecting surface for the purposes noted. As will be readily apparentfrom the illustrations of FIGS. 1 and 2, radiant heat energy will betransmitted from the bank of lamps as a generally uniform, i.e.non-focused, radiant energy field. That is, the radiant heat source 12defined by the plurality of lamps 13 seen in FIGS. 1 and 2 emits radiantheat energy therefrom upwardly as a generally uniform field, as opposedto focused energy which characteristically is emitted from a pointenergy source.

The lamps preferably employed with the present apparatus and thoseillustrated in the drawings are high intensity tungsten filament lampshaving a transparent quartz envelope and a halogen gas containedtherein, preferably iodine. Such lamps are manufactured by theAerometrics Division of Aerojet-General Corporation. Similar lamps areproduced by General Electric Corporation.

The lamp employed in the embodiment of FIGS. 1 and 2 is constructed tobe mounted upright but in another embodiment to be described hereinafteranother configuration may be utilized.

Because of the substantial temperatures at which such lamps operate,e.g., 5000°-6000° F., means are provided in conjunction with the housingand with the lamp mounting blocks to cool the housing walls and theareas surrounding the lamp sockets to prevent overheating of theapparatus. As noted best from FIG. 2, such cooling means for the wallsincludes a plurality of parallel cooling fluid conduits 20 through whichwater or a like cooling medium is circulated. Similar cooling conduits18 are provided in the top closure of the housing. Such conduits may beoperatively connected with a supply of cooling fluid and a disposalsystem therefor in known fashion.

Also, preferably, fluid cooling conduits 19 are provided betweenadjacent rows of the bank of high intensity lamps as seen best in FIG.2. Such conduits 19 are similarly connected with the supply of thecooling medium employed and a disposal system therefor.

The cooling means also preferably includes air circulation means whichin the embodiment shown comprises a pair of adjacent cooling air plenumchambers 21 and 22 extending through the lamp mounting blocks 16adjacent the base thereof. Such plenum chambers are operativelyconnected directly with the sockets 14 in which the lamps are receivedas well as with other vertically and laterally extending channels 23which similarly extend longitudinally of the lamp mounting blocks. Thus,cooling air is forced to circulate around the lamps and through thehollow interior 7 of the housing for subsequent discharge through anexhaust port 25 in communication with an exhaust system (not shown).

Positioned within the hollow interior of the housing is a structurewhich defines the reaction zone of the present apparatus in which theepitaxial coating are deposited on substrates positioned therein. Suchreaction zone is generally designated 31 and comprises a reactionchamber defined by an elongated generally enclosed tubular structureselectively formed from a material which is transparent to the shortwave length heat energy generated by the heat source 12 previouslydescribed. In its preferred form, such reaction chamber has its wallsformed from quartz which is transparent to radiation energy in the onemicron and below range. The tube is generally rectangular incross-sectional construction and the dimensions thereof may varyaccording to particular production needs. However, one such tube havingdimensions of 2 inches by 6 inches with the length being determined inaccordance with production requirements may be employed.

As seen in FIG. 1, one end of the reaction tube is operatively connectedat 24 with an exhaust hood 26 which in turn is connected with theaforementioned exhaust system so that spent reaction gases may bewithdrawn from the reactor. At its opposite ends, the gaseous reactantsto be employed in the coating procedure are introduced into the reactionchamber through means which, in the embodiment illustrated, comprises apair of conduits 32 and 33 which pass through a portion 34 of the endwall 8 of the reactor and terminate within a mixing chamber 36 definedby a baffle plate 37 and the end wall portion 34. The gaseous reactantsemanate from tube 32 through a series of openings 38 provided thereinadjacent the baffle plate while the end 39 of the other tube 32 is opendirectly into the mixing chamber. Following thorough mixing of thevarious reactants in the mixing chamber, the same pass beneath thebaffle plate through a slotted passageway 41 provided therebetween andthe bottom wall of the reaction chamber as seen in FIG. 1. It should beunderstood, of course, that the particular means chosen for introducingthe gaseous reactants into the reaction chamber may be varied to meetparticular manufacturing and production requirements.

Supported within the reaction chamber in the preferred embodiment shownis an elongated slab-like susceptor 42 on which a series of silicon orlike wafers 43 are supported in spaced relationship. As seen from FIGS.1 and 2, susceptor 42 is positioned directly above and in line with theheat source 12 so that the field of radiant energy emitted by the heatsource passes directly through the wall of the reaction chamber into thedirect contact with the under surface of the susceptor to directly heatthe susceptor over its full extent. The size of the susceptor iscorrelated to the size of the quartz reaction chamber and may vary tomeet particular commercial needs. It should also be understood that incommercial reactors, more than one reactor station may be provided sothat treatment of one batch of wafers in one reaction chamber may beprogressing while another reaction chamber is being loaded or unloaded.

Preferably susceptor 42 is supported above the bottom wall of thereaction chamber and for that purpose a supporting stand of any suitableconstruction may be provided, such as the elongated H-shaped stand 44illustrated in FIG. 2. Preferably such a stand is transparent to theradiant energy emitted by the heat source and as such may be formed ofquartz. While it is a requirement that the susceptor material employedby opaque to the radiant energy emitted from the heat source, variousmaterials may be employed in that regard. In the preferred embodiment,such susceptor preferably is produced from graphite which readilyabsorbs radiant heat energy at the short wave length noted. However, itis not a requirement that the susceptor be electrically or thermallyconductive. By utilizing a susceptor, uniform heating of the waferspositioned therein is insured.

In certain embodiments of this apparatus it is visualized that thewafers may be directly heated in the reaction chamber without asusceptor by supporting the wafers directly on the bottom wall of thechamber. However, such a procedure is less desirable but, because of theopaque nature of the wafers, such a procedure will produce acceptableresults although utilization of a susceptor as noted is highlypreferable.

The reaction chamber 31 may be supported in any suitable fashion withinthe housing. In the generally schematically embodiment shown, a seriesof projecting supports, designated 46, are positioned at intervals alongthe length of the reactor as best seen in FIG. 2 and the reactionchamber rests upon such supports. Such supports may be formed fromquartz to prevent their interferring with effective heat transmission.

The alternate embodiment shown in FIG. 3 is in all important respectsthe same as that described previously in FIGS. 1 and 2 withmodifications being evident in conjunction with the heat source,generally designated 51, in FIG. 3. Such heat source comprises at leastone and preferably a bank of high intensity lamps 52 which generate afield of non-focused radiant heat energy of the type describedpreviously. However, the individual lamps 52 differ from those lamps 13described previously in that each comprises an elongated tubularconfiguration which extends through opposite sidewalls thereof to bereceived within opposite spring mounting means 53 and 54 each defined bya socket 56 in which an end of the lamp is positioned. A pair of springs57 and 58 are suitably anchored at 59 and 61 in brackets secured to ahousing wall. The electrical connections for the lamps 52 have not beenillustrated but such connections are of conventional construction.

It should be understood that a series of such lamps 52 are mounted asnoted in generally parallel relationship and extend at spaced intervalsacross the housing at longitudinally spaced positions therealong toproduce the generally uniform energy field noted.

Cooling water and cooling air means are provided for the purposes notedpreviously. The cooling water conduits 18 and 20 are arrangedessentially the same as described previously with respect to FIG. 2.However, some modification in the cooling air arrangement isnecessitated because of the different construction of the lamps 52. Inthat regard, an enlarged plenum chamber 62 extends along the base of thehousing and a series of air passages 63 extend through the bottom wall64 of the housing defined by a polished metal plate so that cooling airmay pass upwardly around the respective lamps and pass from the hollowinterior of the housing into the exhaust system in the manner notedpreviously.

Lamps of the type shown at 52 are produced by General Electric asillustrated in their brochure No. TP-110 entitled "Incandescent Lamps"and marketed under the trademark "Quartzline".

FIGS. 4 and 5 illustrate a further modification of the subject radiationheated reactor in which the reactor construction is substantiallydifferent from that described previously but in which the epitaxialcoating procedure corresponds to that described previously. As seen inFIG. 4, the reactor includes a support 66 to be positioned within andsupported within a housing enclosure (not shown). The heat source,generally designated 67, in this embodiment comprises a cylindrical lampmounting block 68 having a hollow interior 69 as best seen in FIG. 5. Inthe upper surface of the lamp mounting block are a series ofsemi-spherical recesses 71 in which a plurality of high intensity lamps70 of the type shown and described previously with respect to FIG. 1 arepositioned.

The number of lamps 70 chosen depends upon the scope of the commercialoperation intended for the reactor. It should be understood thatsuitable socket openings communicate with the semi-spherical recesses toaccommodate the lamps therein in generally the same manner as shown inFIG. 1. The upper surface 72 of the lamp mounting block, as well as thesurfaces of the socket recesses 71 are highly polished so as to behighly heat reflective. Thus, as is evident from FIG. 5, a generallyuniform field of radiant heat energy will be emitted upwardly by thebank of lamps 70.

The lamp mounting block is supported above the support plate 66 in anysuitable fashion. In that regard, conduits 73 and 74 are spacedlysecured to the base of the lamp mounting block and pass through thesupport plate 66 and are rigidly connected with the support plate so asto position the lamp mounting block above the support plate as noted inFIG. 4. The respective conduits 73 and 74 provide water cooling inletsand outlets which communicate with internal circulating channels 75formed within the mounting block. Although not shown, if desired, aircooling means may be provided in conjunction with the respective lampsockets also, in the fashion described herein previously.

The reaction chamber of this embodiment is defined by an outer bell jar76 of conventional configuration and construction which rests upon thesupporting plate 66 and completely encloses the heat source and theremaining reactor structure to be described. The inner portion of thereaction chamber is defined by a quartz shroud 77 which is hollowcylindrical in configuration, and donut shaped so that inner portion 78thereof fits within the bore 69 of the lamp mounting block as best seenin FIG. 4. Thus, the shroud completely separates the lamps and the lampmounting block and associated structure from the hollow interior of thereaction chamber defined by the shroud and the surrounding bell jar.

This embodiment also uses an opaque susceptor of graphite or the likeand such susceptor is in the form of a circular ring plate 81 secured inany suitable fashion to and supported by a hollow shaft 82 whichprojects upwardly through the support plate 66 of the reactor as seen inFIG. 4. Shaft 82 is rotatable at relatively slow speeds (e.g., 10 to 15revolutions per minute) by means of any suitable gearing or motor drive(not shown) so that the susceptor and a supply of wafers 83 supportedthereon are carried in a moving path above the heat source defined bythe bank of lamps shown. The purpose of such movement relative to theheat source is to insure uniform heating of the susceptor and the waferscarried thereby by the field of energy impinging upon the outer surfaceof the susceptor. Access to the susceptor is had by lifting the belljar.

The hollow shaft 82 further defines conduit means for introducinggaseous reactants into the reaction chamber for epitaxial reactiontherein with the wafers 83. The spent reaction gases pass from thereaction chamber through a vent port 84 provided in the support plate 66from which they pass into any suitable exhaust system (not shown).

A further embodiment of the subject radiation heated reactor isillustrated in FIGS. 6 and 7. Such arrangement comprises a supportingplate 91 which is mounted within an enclosure (not shown) in anysuitable manner. Projecting upwardly through the supporting plate 91 isa shaft 92 designed to be rotated by any suitable means (not shown).

Supported upon the upper end of shaft 92 is a generally cylindricalopaque susceptor of graphite or the like, designated 93. As seen in FIG.7, the outer periphery of the susceptor is provided with a series ofrecesses 94 in which wafers to be epitaxially coated are positioned ingenerally vertical orientation. The inner wall 97 (FIG. 7) of eachrecess is inwardly inclined away from the vertical to insure retentionof a wafer therein during rotation of the susceptor. In that regard,relatively slow rotation in the range of approximately 10 to 15revolutions per minute is utilized. Rotation of the susceptor isprovided to insure uniform heating of the susceptor by the heat source.

With this embodiment, the reaction chamber is defined by a quartz belljar 98 of conventional construction and configuration which surroundsthe susceptor and rests on the supporting plate 91 as seen in FIG. 6.Access to the susceptor is had by raising the bell jar.

The heat source, generally designated 99, employed in this embodimentcomprises a cylindrical ring-shaped lamp mounting block 101 in which aseries of high intensity lamps 102 are positioned in vertically spacedrows in the manner shown. The semi-spherical sockets from which thelamps project and inner periphery of the lamp block 101 are highlypolished for the purpose noted previously.

Thus, the illustrated lamp bank surrounds the susceptor and directs agenerally uniform field of radiant heat energy against the susceptorabout its entire periphery as is apparent from FIG. 6. The lamp bank isoperatively separated from the susceptor by the reaction chamber definedby the bell jar 98. The lamp block 101 is provided with means forcooling the same in the form of a helical coil 103 which surrounds thesame through which a cooling fluid such as water may enter at one end104 thereof and exit at the other end 106 thereof. Cooling air also maybe introduced through the lamp mounting block if desired.

The gaseous reactants are introduced through a suitable port structure107 provided in plate 91 and the spent reaction gases exit from thereaction chamber through a port structure 108 for passage into asuitable exhaust system.

Having thus made a full disclosure of various embodiments of improvedapparatus and process for epitaxially coating substrates, reference isdirected to the appended claims for the scope of protection to beafforded thereto.

We claim:
 1. A cool wall radiation heated reactor for effectingepitaxial and like chemical vapor deposition reactions therein on heatedsubstrates positioned therein and heated thereby, comprisingA. a radiantheat source defined by a bank of a plurality of high intensity radiantheat lamps which together produce and transmit radiant heat energy ofshort wave length as a generally uniform non-focused radiant energyfield, B. means defining a reaction chamber, for receiving therein thesubstrates to be coated, positioned adjacent said heat source,1. atleast that portion of a wall of said reaction chamber which ispositioned adjacent said heat source being formed from a material whichis transparent to heat energy at the wave length produced by said heatsource so that such radiant energy is transmitted through said wallwithout appreciable absorption thereby, whereby said wall remains cooland substantially free of film deposits during operation of saidreactor, C. susceptor means to be heated directly by said field ofradiant energy emitted from said heat source, said susceptor means beingpositioned within said reaction chamber for supporting said substratesdirectly thereon in direct contact therewith during operation of saidreactor,
 1. said susceptor means including a susceptor body formed froma material which is generally opaque to said radiant energy and whichabsorbs the same and is generally uniformly heated thereby,2. saidsusceptor body being positioned directly in line with said energy fieldemitted by said heat source for direct heating thereby over its fullextent,
 3. said susceptor body in turn uniformly heating and maintainingthe temperature of said substrate substantially constant duringoperation of said reactor, and D. conduit means for introducing gaseousreactants into said reaction chamber and for withdrawing spent reactiongases therefrom.
 2. The reactor of claim 1 in which said bank of lampsis positioned below said susceptor body so that said susceptor body isinterposed said lamps and the substrates supported by said susceptorbody.
 3. The reactor of claim 1 in which said bank of lampssubstantially surrounds said susceptor body and the substrates supportedthereon.
 4. The reactor of claim 1 which further includesE. means formoving said susceptor body relative to said heat source to insuresubstantially uniform heating of said susceptor body.
 5. The reactor ofclaim 4 in which said moving means includes mechanism for rotating saidsusceptor body relative to said heat source.
 6. The reactor of claim 1in which said susceptor body comprises1. a generally cylindrical bodyhaving substrate receiving recesses in the outer periphery thereof, and2. means for rotating said body, and in which said heat sourcecomprises1. said bank of high intensity lamps surrounding said body andseparated therefrom by said wall portion of said reaction chamber. 7.The reactor of claim 1 in which said lamps of said heat source eachcomprises a high intensity tungsten filament quartz-iodine lamp whichgenerates radiant energy at a wave length of approximately one micron orbelow.
 8. The reactor of claim 1 in which the material from which saidreaction chamber is formed is quartz, and in which said heat sourceproduces radiant energy at a wave length which is not absorbed byquartz.
 9. The reactor of claim 1 which further includesE. means forintroducing a cooling medium against said wall of said reaction chamberwhich is positioned adjacent said heat source to assist in maintainingsaid wall cool to further obviate formation of film deposits on saidwall during operation of said reactor.
 10. The reactor of claim 1 inwhich all walls of said reaction chamber are formed from said materialwhich is transparent to heat energy at said wave length.
 11. The reactorof claim 1 in which each said lamp of said heat source comprises a highintensity lamp which radiates heat energy at a wave length ofapproximately one micron.
 12. The reactor of claim 11 in which saidreaction chamber comprises a quartz enclosure separating said heatsource from said susceptor, the walls of said enclosure being generallyunobstructive of heat energy radiated at said wave length.
 13. Thereactor of claim 1 in which said susceptor means further includes3.structure for moving said susceptor body relative to said heat source toinsure substantially uniform heating of said susceptor body and thesubstrates supported thereby.
 14. The reactor of claim 1 which furtherincludesE. means for introducing a cooling medium into contact with saidradiant heat source.
 15. The reactor of claim 1 in which each said lampcomprises a tungsten filament-halogen lamp.
 16. The reactor of claim 15in which each said lamp comprises a tungsten filament-iodine lamp. 17.The reactor of claim 1 in which said susceptor means is separable fromsaid reaction chamber so that said substrates may be positioned on saidsusceptor body outside said reaction chamber and thereafter introducedon said susceptor body into said reaction chamber.
 18. The reactor ofclaim 1 in which said susceptor body is generally cylindrical inconfiguration and includes means in conjunction therewith definingrecesses therein for receiving said substrates therein, and in whichsaid bank of lamps is positioned to surround said susceptor and directheat energy at said wave length inwardly against said susceptor body andthe substrates supported thereby.
 19. The reactor of claim 18 whichfurther includesE. mechanism for rotating said susceptor body which saidbank of lamps surrounding the same.